Immortality of all cancer cells exposed as a myth

FAR from being immortal, most cancer cells seem unable to multiply limitlessly and spread throughout the body.

Dot Bennett of St George’s University of London and colleagues found that only four of 37 skin cancer samples they examined displayed the supposed hallmark of cancer.

By studying the molecular profiles of the cancer cells as they grew in the lab, the team found that many appeared to have hit a “telomere crisis” and stopped dividing. Telomeres are the caps that protect the ends of chromosomes and they shorten every time a cell divides. In a telomere crisis, the tips become so short that the cell mistakes them for DNA breaks and tries to repair them, generating freak cells that die or become dormant.

The team found that the few cancer cells that seem immortal activate telomerase reverse transcriptase (TERT), a part of the telomerase enzyme that rebuilds telomeres so they avoid a telomere crisis (Pigment Cell & Melanoma Research, DOI&colon; 10.1111/j.1755-148X.2011.00850.x).

Normally, TERT is active only in sperm or egg cells, so looking for it in a tumour could tell doctors whether the cells are immortal and more likely to spread, helping them decide on the best treatment.

Last week, Cancer Research UK launched a trial to stop pancreatic cancer spreading with a vaccine composed of fragments of TERT. The body’s immune system would recognise the TERT as foreign and mobilise to attack it, bringing all pancreatic cancer cells with active TERT into the firing line too.

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